1. Field of the Invention
This invention relates to systems and methods employing the encoding of scattered gamma fluxes for determining three-dimensional density distributions within an object or body to identify the presence of contraband within the object, or to identify internal characteristics within the object or body, or to detect medical abnormalities in a human body.
2. Description of the Related Art
There is a recognized and growing need for improved capability to “see” inside closed boundaries of objects and for accurate measurement of their internal characteristics. For instance, inspection devices are needed to examine baggage and containers to enhance security and search for contraband at airports, government facilities, public buildings, and other possible targets of terrorism. Inspection devices can be installed at check points to scan baggage and other types of containers so that their contents can be characterized and inspected for contraband such as explosives, weapons, drugs and other illicit substances. Non-invasive inspection devices have also become an important tool for on-line monitoring of characteristics of materials undergoing industrial processing within tanks and pipes.
In the medical field, inspection devices, especially non-invasive devices, provide many life-saving benefits. They are used by physicians and medical personnel to assist with the diagnosis and treatment of medical abnormalities in a human body and to mitigate the need for expensive and risky surgical procedures.
Imaging inspection systems have evolved from simple X-ray imaging systems providing two-dimensional images, to more sophisticated automated systems capable of three-dimensional imaging. Such current devices and techniques include Computer Assisted Tomography (CAT), Positron-Electron Emission Tomography (PET), and Magnetic Resonance Imaging (MRI). However, these conventional devices and techniques generally rely on multiple sources and/or complex arrays of detectors, and require a relative scanning motion between the inspected object and the principal system components. Such operating conditions result in significant complexity, size, cost, inspection time, and radiation exposure. A need exists for faster baggage-screening devices having good imaging capabilities to detect and identify contraband; detection machines are needed that search and accurately detect a wider range of contraband including nonmetal weapons explosives and components of weapons of mass destruction; further, a need exists for cheaper and smaller inspection devices.